Problem with Nefit Moduline 30 thermostat

[Avandia]

Hi! Sorry, mijn nederlands is heel slecht, dus ik zaal engels spreken. I am having a problem with my thermostat, a nefit moduline 30. As I am going away in a couple of days i do not have time to call a repair man, but as it is so cold I need some heat before I leave! My radiators are only working occasionally, and my thermostat is almost always at 15-15.5 degrees, despite both manual and automatic settings being higher (18-20 degrees) My hotwater and gas is fine and boiler was serviced in november and there was no problem. The heating has been fine until yesterday. If anyone could make suggestions as to how I could solve this it would be much appreciated!